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Number Systems. ELEC 311 Digital Logic and Circuits Dr. Ron Hayne Images Courtesy of Cengage Learning. Admin. Course materials available online http://ece.citadel.edu/hayne/ Students are encouraged to print lecture slides in advance and use them to take notes in class.
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Number Systems ELEC 311 Digital Logic and Circuits Dr. Ron Hayne Images Courtesy of Cengage Learning
Admin • Course materials available online • http://ece.citadel.edu/hayne/ • Students are encouraged to print lecture slides in advance and use them to take notes in class 311_01
Analog versus Digital • Analog • Continuous • Time • Magnitude • Digital • Discrete • 1, 0 • High, Low • True, False 311_01
Digital Circuits • Combinational Circuits • Logic Gates • AND • OR • NOT • Sequential Circuits • Flip-flops • Stores State • Memory 311_01
Computer-Aided Design Tools • Minimization of Logic Equations • Schematic Capture • Synthesis Tools • Hardware Description Languages (HDLs) • Generation of Bit Patterns for PLDs • Programmable Logic Devices • Test Generation • Simulation 311_01
Number Systems • Decimal (Base 10) 953.7810 = 9x102 + 5x101 + 3x100 + 7x10-1 + 8x10-2 • Binary (Base 2) 1011.112 = 1x23 + 0x22 + 1x21 + 1x20 + 1x2-1 + 1x2-2 = 8 + 0 + 2 + 1 + 1/2 + 1/4 = 11.7510 311_01
Number Systems 311_01
Hexadecimal 311_01
Decimal to Binary Conversion • Decimal Integer • Successive Division by 2 (Collect the Remainders) • Successive Subtraction (Powers of 2) • Decimal Fraction • Successive Multiplication by 2 (Collect the Integers) • Successive Subtraction (Powers of 2) 311_01
Binary Addition (Full Adder) 311_01
Binary Multiplication • Multiplication Table 0 x 0 = 0 0 x 1 = 0 1 x 0 = 0 1 x 1 = 1 311_01
Negative Numbers 311_01
2’s Complement • MSB serves as sign bit (fixed-width) • 0 => positive • 1 => negative • Negation Operation • Complement all bits • Add 1 • Alternate Negation Operation • Starting from right to left • Copy up to and including the first 1 • Complement the rest 311_01
Overflow • Operation produces a result that exceeds the number system • Example (4-bits) • Range -8 to +7 • Detection Rule • Overflow occurs if the addends’ signs are the same, but the sum’s sign is different from the addends’ 311_01
Binary-Coded Decimal (BCD) • Encodes digits 0 thru 9 • 4-bit unsigned binary • 0000 thru 1001 • 6 unused code words • 1010 thru 1111 • Packed BCD • 8-bit byte • 2 BCD digits 311_01
Binary Codes 311_01
ASCII Code (Table 1-3) 311_01
Summary • Number Systems (Conversions) • Binary • Hex • Negative Numbers • Sign and Magnitude • 2’s Complement • Arithmetic • Addition (Subtraction) • Multiplication • Codes • BCD • Gray Code 311_01